The present invention generally relates to object collision detection and, more particularly, relates to a vehicle collision detection system and method of estimating the closest point of approach (miss distance) of an object.
Automotive vehicles are increasingly being equipped with collision avoidance and warning systems for predicting the potential collision with an external object, such as another vehicle or a pedestrian. Upon detecting a potential collision, such systems typically initiate an action to avoid the collision and/or provide a warning to the vehicle operator. Adaptive cruise control systems have been proposed to track a leading vehicle and automatically control the speed of the following vehicle. The ability to accurately predict an upcoming collision also enables a vehicle controller to control and deploy safety-related devices on the vehicle. For example, upon predicting an anticipated collision or near collision with an object, the vehicle seat belt pretensioner could be activated in a timely manner to pretension the seat belt, thereby enhancing the application of the safety device. The controller could also deploy a warning signal to notify the vehicle driver of a predicted collision with an object.
In conventional vehicle target tracking systems, the host vehicle is generally equipped with a sensor arrangement that acquires range, range rate, and azimuth angle (i.e., direction to target) measurements for each tracked target within a field of view. The sensor arrangement employed in many conventional collision detection systems is generally complex and costly and includes a plurality of radar beams or laser beams covering a field of view. In order to detect an anticipated vehicle collision with an object, the conventional collision detection system generally senses the presence of an object, tracks the movement of the sensed object, and measures the azimuth angle of the object, range to the object, and range rate of the object, all relative to the host vehicle.
The above-mentioned prior known collision detection systems generally require relatively complex and expensive sensor arrangements which use multiple sensors that are required to measure the azimuth angle of the object, relative to the host vehicle, in addition to obtaining the range and range rate measurements. It is generally desirable to reduce the complexity and cost of systems and components employed in automotive vehicles. It is therefore desirable to provide for a vehicle collision detection system which is able to estimate miss distance of an object and predict a potential collision with an approaching object that offers reduced complexity and cost.
In accordance with the teachings of the present invention, a collision detection system and method of estimating a miss distance of an object are provided. According to one aspect of the present invention, the collision detection system includes a sensor for sensing an object within a field of view. The sensor measures range and range rate of the sensed object. The collision detection system further includes a controller for computing the product of range and range rate and estimating a miss distance of the object as a function of the range and product of range and range rate. According to the embodiment shown, the controller computes a mathematical square of the range and computes a mathematical square of the product of range and range rate for each of a plurality of measurements, and estimates the miss distance of the object as a function of the computed squared range and the squared product of range and range rate.
According to another aspect of the present invention, a method of estimating a miss distance of an object is provided. The method includes the steps of sensing the presence of an object, tracking the sensed object, measuring range to the object for each of a plurality of measurements, and determining range rate of the object for each of the plurality of measurements. The method also includes the steps of computing the product of range and range rate and estimating a miss distance of the object as a function of the range and the product of range and range rate. According to the embodiment shown, the method computes a mathematical square of the range and computes a mathematical square of the product of range and range rate for each of the plurality of measurements, and estimates the miss distance of the object as a function of the computed squared range and the computed squared product of range and range rate.
Accordingly, the collision detection system and miss distance estimation method of the present invention advantageously estimates a miss distance of an object without requiring a complex and costly sensor arrangement, such as those which determine an azimuth angle measurement of the object.